1. Field of the Invention
The present invention relates generally to sealing devices for pipes and specifically to a sealing gasket for sealing off a joint between a socket end and an insert end of two cooperating pipes.
2. Description of the Prior Art
The pipe gaskets of the present invention are especially intended for use in water pipes. In joining such pipes, especially formed from plastic material, it is often preferred to position the sealing gasket for sealing the pipe joint in a groove provided in the outer pipe at the manufacturing site. However, it has been difficult to provide pre-installed gaskets which were securely retained in the outer pipe groove during transport and handling of the pipes. The problem of retaining the sealing gaskets during the joining of such pipes is further complicated where the outer pipe groove has a bottom surface which is at least partly of a rounded shape, rather than being square or rectangular in an cross-sectional area. In the case of grooves having a partly rounded bottom surface, insertion of the inner pipe within the mouth of the outer pipe tend to twist or dislodge the sealing gasket so that the gasket fails to perform the intended sealing function.
U.S. Pat. No. 4,379,559, issued Apr. 12, 1983, entitled "PIPE SEALING DEVICE" to Bohman, shows a sealing device utilizing a retainer ring or band made of a rigid material which cooperates with a sealing ring formed from a more resilient material. The retainer ring is received within a groove in the sealing ring and helps to maintain the position of the sealing device in the outer pipe groove during installation of the inner pipe.
The present invention has as its objective the provision of a seal gasket which is of unitary design and which eliminates the need for a separate retaining ring.
Another object of the invention is the provision of a sealing gasket formed from a unique combination of materials and having a specialized geometry which insures that the gasket will be retained within the outer pipe groove during installation of the inner pipe in forming a water tight pipe joint.
Additional objects, features and advantage will be apparent in the written description which follows.